Research on Output Voltage Self-Balance Control Method of Bipolar DC Distribution Grid for Renewable Energy Consumption

Abstract

Changes in the positive and negative DC loads of bipolar DC distribution grid cause the voltages of DC buses to deviate from the rated value, resulting in additional losses due to unbalanced current and affecting the reliable operation of the distribution grid. This paper proposes an output voltage self-balance control method based on a neutral-point-calmed triple active bridge (NPC-TAB) converter in a bipolar DC distribution grid. First, the topology and operating principle of NPC-TAB are introduced. Then the power model of the topology is deduced based on the phasor method. Based on the above analysis, an output voltage self-balance control method is proposed with the minimization of reactive power to achieve the self-balance of output voltage while controlling the minimization of reactive power of the converter. Finally, the simulation model is established in MATLAB/Simulink to verify the effectiveness of the optimal control method.